<!doctype html>
<html>
<head>
<meta charset="utf-8">
<script>
addEventListener("load", () => {
  getSelection().collapse(document.querySelector("header"), 1);
  getSelection().modify("move", "backward", "line");
  const ruby = document.querySelector("ruby");
  ruby.parentElement.replaceChild(document.createElement("h3"), ruby);
  getSelection().modify("extend", "backward", "character");
});
</script>
</head>
<body>
<textarea>
</textarea>
<abbr>
<header>
<select autofocus='false'>
<input/>
<sup>
<ruby id='a'>
</body>
</html>
